We have recently shown that benzodiazepines such as diazepam endowed with anxiolytic activity, inhibit post tetanic potentiation (PTP) of fast excitatory post synaptic potentials in bullfrog sympathetic ganglia, without altering the responses to single shocks. In addition, diazepam, like GABA and dibutyryl cGMP, depolarizes presynaptic nerve terminals. The bullfrog and rat superior cervical ganglion (SCG) accumulate exogenous GABA, presumably in the glial cells. This radioactive GABA can be released by dibutyryl cGMP, high concentration of K ion and diazepam. Rat SCG contain endogenous GABA that can be altered by various drugs and other treatments. We postulated that diazepam acts presumably by releasing glial GABA which depolarizes presynaptic terminals and inhibits transmitter release, thus inhibiting PTP. However, the mechanism by which cyclic nucleotides contribute to the action of anxiolytics remains obscure. The objective of this proposal is to investigate the possibility that anti-anxiety drugs decrease synaptic transmission by a mechanism involving modulation of cyclic nucleotide metabolism. In addition, the dynamic relationship between cyclic nucleotides and GABA and the manner this relationship is modified by anti-anxiety drugs will be studied. Cyclic AMP and cyclic GMP present in tissues will be separated and quantified by their ability to activate protein kinase. GABA in the tissues will be estimated by high pressure liquid chromatography. Using these techniques we will determine the levels of cyclic nucleotides before and after ganglionic stimulation in the presence and absence of anti-anxiety drugs. Pharmacological manipulations of cyclic nucleotide metabolism will be carried out and both cyclic nucleotide and GABA levels will be estimated. Similarly GABA metabolism will be altered and cyclic nucleotide levels will be monitored. Appropriate dose-response relationships between anti-anxiety drugs and levels of cyclic nucleotides and GABA will be constructed. Using appropriate drug concentration, the effects on cyclic nucleotide metabolism with respect to GABA will then be studied. This study will help gain some insight as to the mechanism by which anxiolytics may involve cyclic nucleotides and GABA in their action thus contributing to the better understanding of their mechanism of action.